Process of making plywood tubes



Jan. 24,1928. 1,657,280

J. H. PROCTOR PROCESS OF MAKING PLYWOOD TUBES Original Filed Aug- 10, 1921 2 Sheetsheet 1 INVENTOR.

Jan. 24, 1928.

1,657,280 J. H. PROCTOR PROCESS OF MAKING PLYWOOD TUBES Original Filed Aug. 10. 1921 2 sheets-sheet 34 30 a4 a5 34 2 PM ;x W l&\\\\\\\\\\ 4 \i Mammy w m f7 INVEN'I'OR.

Patented Jan. 24, 1928.

UNITED STATES PATENT OFFICE.

JOHN H. PROCTOR, OF ANDOVER, MASSACHUSETTS, ASSIGNOR TO THE PLYWOOD TUBE,

INC,, OF LAWRENCE, MASSACHUSETTS,

A CORPORATION OF MASSACHUSETTS.

PROCESS OF MAKING PLYWOOD TUBES.

Original application filed August 10, 1921, Serial No. 491,234. Divided and this application fled May 31,

. 1923. Serial No. 642,491.

manufacture of textiles for use as rolls,

beams, spools, bobbins, and other similar articles for winding textile material, and may also be used for conduits and insulators for electric wires, and even for broom and mop handles.

Broadly speaking, my invention consists of forming a tube by winding spirally, preferably on a'mandrel, a thin sheet of wood such as is known as veneer, preferably of the rotary cut type, the spiral of wood having between its layers an lntervening spiral layer of glue, preferably of a waterproof type.

Preferably, such tubes are made by winding the wood with intervening glue under 5 pressure upon a core shell which is preferably of the expanding type, and retaining the tube under pressure until the glue has set. I prefer not only to wind the wood under pressure but when the tube has been built up, to expand the core shell from the interior after the tube has been placed in a mold whereby the outer surface can be expressed or molded with a firm, smooth finish, without creases.

As is well known in the trade, there are now recognized three types of veneer. These are, first, that sliced with the grain; second, sawed with the grain; and third, rotary out, where the log is held at each end between centers on the lathe and revolved against a knife which shaves off a thin continuous strip without waste, the grain of such strip running crosswise of the cut sheet.

I prefer to use such rotary cut veneer as it is stronger, cheaper, and winds more readily without kinks or bulges.

It is apparent that as the veneer is cut from the log it would naturally assume the spiral in which it lay in the 10 and that if it is flattened out, as it would be on a table or when passed between rolls, the pores in the concave side tend to open and small fis sures form on that side. On the other hand, if it is wound with the concave side nearer the axis into a tube which is smaller than the original scroll, the pores and fissures on the outer or convex side tend to open while those on the concave side are forced together.

I prefer to first straighten out my sheet of veneer by passing it through rollers and, while straightened out, to spread glue on the concave side by means of a pressure roller while the fissures on that side are open. I then prefer to wind it under pressure into a smaller roll whereby the glue in the fissures on the concave side is compacted and the glue is forced into the fissures which form on the convex side.

As it is apparent that such fissures occur at the relatively weakest spots, and as the glue used is stronger than the wood, the resulting tube, having its weak spots reinforced and being bound together by the glue with the grain of the wood naturally crossmg more or less, is much stronger than a similar tube turned on a lathe from solid wood.

It is also apparent that, ordinarily in wood, a flaw or weak grain weakens the wood to a greater depth than the thickness of a veneer of one thirty-second to one sixtyfourth inch, and that by displacing these weak'spots by wrapping the veneer in a spiral they do not register in spiral layers, and greater resulting strength is obtained than in solid wood.

It is also a fact that the grain of most woods does not lie in straight and parallel lines but curves materially, and I take advantage of this irregular grain.

I am well aware that tubes have been built up of several layers of veneer wound helically and otherwise, with the grain of different layers crossing, but I claim to be the first to make a cheap tube of sufficient strength for many practical urposes by winding up a single sheet of rotary cut veneer with its convex side out, in a single spiral around a suitable core.

More particularly I claim to be the first to so wind under pressure and to take the resulting tube and subject it to either additional interior or exterior pressure or both until the glue sets.

In the drawings, Fig. 1 is a diagrammatic representation of the manner in which rotary cut veneer is out from the log.

Fig. 2 is a small magnified longitudinal side view of rotary cut veneer showing in dotted lines the natural curve and in full lines the curve when wound to a smaller diameter.

Fig. 3 is a diagrammatic side view of a machine which may be used for spreading glue and rolling my tubes.

Fig. 1 is a much enlarged longitudinal side view showing rotary'cut veneer flattened out.

Fig. 5 is a vertical section showing one form of expansible core, and

Fig. (i is a view from the left end thereof.

Fig. 7 is an end view of one form of pressure mold.

Fig. 8 is a pcrspcrtivc view partly in section showing a tube of my construction.

Fig. 9 is an exaggerated and enlarged end view illustrating the manner in which a tube of my construction is formed.

Fig. 10 is a vertical sectional view of a broom handle.

Fig. 11 is a vertical sectional view of one type of bobbin.

Fig. 12 is an elevation partly in section of another type of bobbin.

Fi 13 is a view from the left of Fig. 12.

Fig. 141 is an elevation partly in section showing the end of a spool.

Fig. 1 shows diagrammatically how the sheet of rotary cut veneer A is cut from the log 10 by means of a knife 11 in a well known manner. I will call 12 the outside, convex or face side, and 13 the concave, inside or back of the sheet. The grain of irregular formation is shown at 14-.

As shown in Fig. 2, when such a sheet of veneer A, whose normal curve is shown by the dotted lines, is bent to a smaller curve as it generally would be for forming small tubes such as bobbins or broom handles, outside fissures indicated at 15 occur in irregular lines around the outside.

In Fig. 3, I show diagrammatically how such a sheet of veneer A is wound on a mandrel B. This mandrel may be rotated in any suitable machine in contact with a pressure roll C which is forced against it by means of a spring 20. Mandrel 1) serves as a core and is preferably of the expansible type, such as shown more in detail in Fig.

I find a convenient form of winding is to use a belt 21 which passes over pulleys 21 23 and 24, as well as mandrel B, whereby the sheet A can be fed around with a belt 21 and may be separated therefrom by a suitable guide 25 which carries it along and causes it to wind in a spiral.

The veneer A is fed between the rollers 26 and 28 with its concave surface or back 13 at the top, and its convex surface at the bottom, and as it is straightened out between these rollers and mandrel B, small fissures shown at 16 in Fig. 4 develop and these are filled with the glue 2? as it passes between rollers 26 and 28.

A roller 26 may be used to spread glue, indicated at 27, evenly on sheet A in any well known manner. The machine for winding is immaterial, as in fact it might be wound upon a hand mandrel or core with manual pressure on a suitable table, if such method were not too uncertain and expen- SIVG.

An expansible mandrel B is shown in Fig. 5 as comprising an outer shell 30 of split steel tubing, a spindle 31 having annular shoulders 32, 32, and a threaded end 33 together with tubular wedges 3 1, 3 1, 34, an expanding nut 35 threaded on the end till and a removable handle 36 whereby each nut 35 can be turned so as to force the wedges 3 1 and 34 together thereby expanding the shell 30 and with it the tube.

In Fig. 7, I show a mold I) in which the core B and tube E can be placed. Mold 1) comprises two halves 40 and 41 hinged at 42, one being provided with bolt 13 pivoted at 44c and the other with a slot 45 in which bolt 43 can enter, together with a not all whereby exterior pressure can be applied if desired.

In Fig. 8, I show a tube made in accordance with my invention which may be used for any purpose for which tubes are used, the spiral layers of veneer being shown at and the intervening spiral layers of glue being shown at 51. Such a tube may be used for warp beams, conduits, and various other purposes.

In Fig. 10, I show an ordinary broom handle made up of a tube indicated at 54. and preferably having a head and lug 56.

In Fig. 11, I show a type of bobbin used in textile machinery having a very thin wall and a relatively small head. This bobbin is indicated at H, the barrel being smooth and thin. The head 62 might be made separately and put on, as shown in Figs. 12 or 13, or the barrel might be made the size of the head and then turned down as preferred. The plug ()3 completes the bobbin.

In Figs. 12 and 13, I show another type of bobbin having a barrel 66 with corrugations (35, a metal tip 67 and a head (38 which is made by winding a narrow strip of rotary cut veneer around the barrel 66 after the barrel is finished.

Fig. 14 shows a spool L of well known type in textile manufacturing having a barrel 70 threaded at 71 to receive a head 72 shown as made of plywood, the spool being further held together by pins 73.

I show graphically in Fig. 9 the relative positions of the interior fissures 16 and erall Itlll terior fissures 15 as well as the glue 51 which forms the spiral concentric with the sheet of veneer and also fills the fissures 15 and 16.

I prefer to use a waterproof glue of what is known commercially as the casein type, or I may use a glue of the blood albumen type.

It is apparent that I might use my expansible core as a solid core or mandrel instead of an expansible one, and that I might place this in a mold similar to B with or without pressure means, merely holding the tube in position until the glue sets without being under any additional pressure.

I claim:

1. The process of making ply wood tubes which consists of winding spirally under pressure rotary cut veneer upon an expansible core with the average direction of the grain parallel to and what was originally the concave side nearer the axis of the bobbin with intervening layers of Waterproof glue and then expanding the core in a mold and retaining the tube under interior and exterior pressure until the glue sets.

2. The process of making ply wood tubes which consists of Winding spirally under pressure rotary cut veneer on a core with the average direction of the grain parallel to and what was originally the concave side nearer the axis of the tube with intervening layers of glue and then placing the core and tube in a mold until the glue sets.

3. The process of making ply wood tubes which consists of winding spirally under pressure rotary cut veneer upon an ex pansible core with the average direction of the grain parallel to and what was originally the concave side nearer the axis of the tube with intervening layers of waterproof glue and then expanding the core and retaining the tube under interior pressure until the glue sets.

4. The process of making ply wood tubes which consists of winding spirally under pressure rotary cut veneer upon an expansible core with the average direction of the grain parallel to and what was originally the concave side nearer the axis of the tube with intervening layers of waterproof glue and then expanding the core andretaining the tube under pressure until the glue sets.

5. The process of making ply wood tubes which consists of winding spirally under pressure rotary cut veneer upon a core with the average direction of the grain parallel.

to the axis of the tube, with intervening layers of glue and then holding the core and tube in position until the glue sets.

6. The process of making ply wood tubes which consists of flattening out rotary cut veneer and spreading on what was originally the concave side thereof glue under pressure, and of then winding such veneer spirally under pressure upon a core which has a radius which is smaller than the natural radius of the veneer on the log, with the average direction of the grain parallel to and what was originally the concave side nearer the axis of the core, and of retaining the tube in position until the glue sets.

JOHN H. PROCTOR. 

